Danfos, The Influence of Subcooling on Refrigeration Control Quality. Page 6. screw compressor manufacturers offer them with economizer. This systems can use flash-gas for the economizer input.
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Most nuclear power plants do not have an economizer. However, the Combustion Engineering System 80+ nuclear plant design and its evolutionary successors, (e.g. Korea Electric Power Corporation's APR-1400) incorporate an integral feedwater economizer. This economizer preheats the steam generator feedwater at the steam generator inlet using the lowest-temperature primary coolant.
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The low-pressure steam is supplied to the low-temperature turbine. A super heater can be provided in the low-pressure circuit. Some part of the feed water from the low-pressure zone is transferred to the high- pressure economizer by a booster pump. This economizer heats up the water to its saturation temperature.
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High pressure boilers typically have larger economizer surfaces than low pressure boilers. Economizer tubes often have projections like fins to increase the heat transfer surface on the combustion gas side. On average over the years, boiler combustion efficiency has risen from 80% to more than 95%. The efficiency of heat produced is directly linked to boiler efficiency.
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Economizers (US and Oxford spelling), or economisers (UK), are mechanical devices intended to reduce energy consumption, or to perform useful function such as preheating a fluid. The term economizer is used for other purposes as well. Boiler, power plant, heating, refrigeration, ventilating, and air conditioning (HVAC) uses are discussed in this article. In simple terms, an economizer is a heat exchanger.
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The solution is an economizer that adds a second control which works in harmony with the outdoor thermostat and measures the outdoor air humidity.
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It also allows control over the temperature of gases leaving the stack (to meet emissions regulations, for example). It is installed between the economizer and chimney.
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Natural gas has different combustion efficiency curves linked to the temperature of the gases and the excess air. For example, if the gases are chilled to 38 °C and there is 15% excess air, then the efficiency will be 94%. The condensing economizer can thus recover the sensible and latent heat in the steam condensate contained in the flue gases for the process. The economizer is made of an aluminium and stainless steel alloy.
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Economizer screw compressors are being built by several manufacturers like Refcomp, Mycom, Bitzer and York. These machines merge both compressors of a two staged system into one screw compressor and have two inputs: the main suction and an interstage side entrance for higher pressure gas. This means there is no need to install two compressors and still benefit from the booster concept. There are two types of economizer setups for these compressors, flash and subcooling.
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Once this water is inside the boiler or steam generator, the process of adding the latent heat of vaporization begins. The boiler transfers energy to the water by the chemical reaction of burning some type of fuel. The water enters the boiler through a section in the convection pass called the economizer. From the economizer it passes to the steam drum, from where it goes down the downcomers to the lower inlet waterwall headers.
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One of two original 1940s 'Green's Economizers' inside the Killafaddy Board Mills boiler house on the outskirts of LauncestonThe first successful economizer design was used to increase the steam-raising efficiency of the boilers of stationary steam engines. It was patented by Edward Green in 1845, and since then has been known as Green's economizer. It consisted of an array of vertical cast iron tubes connected to a tank of water above and below, between which the boiler's exhaust gases passed. This is the reverse arrangement to that usually but not always seen in the fire tubes of a boiler; there the hot gases usually pass through tubes immersed in water, whereas in an economizer the water passes through tubes surrounded by hot gases.
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The latter works under the same principle as the two staged booster displays with subcooling. The flash economizer is different because it doesn't use a heat exchanger to produce the subcooling. Instead, it has a flash chamber or tank, in which flash gas is produced to lower the temperature of the liquid before the expansion. The flash gas that is produced in this tank leaves the liquid line and goes to the economizer entrance of the screw compressor.
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Heat transfer efficiency is improved when the highest temperatures near the combustion sources are used for boiling and superheating with the cooled combustion gases exhausting from the boiler through an economizer to raise the temperature of feed water entering the steam drum. An indirect contact or direct contact condensing economizer will recover the residual heat from the combustion products. A series of dampers, an efficient control system, as well as a ventilator, allow all or part of the combustion products to pass through the economizer, depending on the demand for make-up water and/or process water. The temperature of the gases can be lowered from the boiling temperature of the fluid to little more than the incoming feed water temperature while preheating that feed water to the boiling temperature.
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Several reheat exceptions were eliminated or modified. Restrictions were placed on overhead air heating. Economizer requirements were added for more climate zones and smaller systems. Class A is now required for all duct sealing.
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All previous systems produce an economizer effect by using compressors, meters, valves and heat exchangers within the refrigeration cycle. Depending on the system, in some refrigeration cycles it may be convenient to produce the economizer using an independent refrigeration mechanism. Such is the case of subcooling the liquid line by any other means that draw the heat out of the main system. For example, a heat exchanger that preheats cold water needed for another process or human use, may withdraw the heat from the liquid line, effectively subcooling the line and increasing the system's capacity.
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An economizer serves a similar purpose to a feedwater heater, but is technically different as it does not use cycle steam for heating. In fossil-fuel plants, the economizer uses the lowest- temperature flue gas from the furnace to heat the water before it enters the boiler proper. This allows for the heat transfer between the furnace and the feedwater to occur across a smaller average temperature gradient (for the steam generator as a whole). System efficiency is therefore further increased when viewed with respect to actual energy content of the fuel.
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This avoided problems of exhaust blowback into the oil-fired flue. Another composite form for ships used two boilers: one of minimal form with a central flue, used as a silencer economizer for the diesel engines, and another as a purely oil-fired central flue boiler. The economizer was used with pumped circulation (as it was usually mounted high up) as a feedwater heater. This system was used where a large amount of steam was required even when in port, such as for heated cargoes like banana boats and passenger liners.
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This increases the rate of heat transfer to the water coming from economizer into evaporating section causing it to generate more steam that goes in superheater via steam separator. Steam from superheater is at high temperature and pressure. This is used to operate turbines.
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With the appropriate controls, economizers can be used in climates which experience various weather systems. For information on how economizers and other controls can affect energy efficiency and indoor air quality in buildings, see the US Environmental Protection Agency report, "Energy Cost and IAQ Performance of Ventilation Systems and Controls Study." When the outside air's dry- and wet-bulb temperatures are low enough, a water- side economizer can use water cooled by a wet cooling tower or a dry cooler (also called a fluid cooler) to cool buildings without operating a chiller. They are historically known as the strainer cycle, but the water-side economizer is not a true thermodynamic cycle.
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A common form of refrigeration economizer is a "walk-in cooler economizer" or "outside air refrigeration system". In such a system outside air that is cooler than the air inside a refrigerated space is brought into that space and the same amount of warmer inside air is ducted outside. The resulting cooling supplements or replaces the operation of a compressor-based refrigeration system. If the air inside a cooled space is only about 5 °F warmer than the outside air that replaces it (that is, the ∆T>5 °F) this cooling effect is accomplished more efficiently than the same amount of cooling resulting from a compressor based system.
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The water enters the boiler through a section in the convection pass called the economizer. From the economizer it passes to the steam drum and from there it goes through downcomers to inlet headers at the bottom of the water walls. From these headers the water rises through the water walls of the furnace where some of it is turned into steam and the mixture of water and steam then re-enters the steam drum. This process may be driven purely by natural circulation (because the water is the downcomers is denser than the water/steam mixture in the water walls) or assisted by pumps.
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Ernest Robert Godward (7 April 1869 – 2 December 1936) was an English born inventor and engineer who lived in New Zealand, England, and the United States. He created the spiral hairpin and a type of carburettor called a petrol economizer, which increased engine performance and reduced fuel consumption.
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While both are heat exchange devices, in a boiler the burning gases heat the water to produce steam to drive an engine, whether piston or turbine, whereas in an economizer, some of the heat energy that would otherwise all be lost to the atmosphere is instead used to heat the water and/or air that will go into the boiler, thus saving fuel. The most successful feature of Green's design of economizer was its mechanical scraping apparatus, which was needed to keep the tubes free of deposits of soot. Economizers were eventually fitted to virtually all stationary steam engines in the decades following Green's invention. Some preserved stationary steam engine sites still have their Green's economisers although usually they are not used.
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Ericsson coined the term "regenerator" for his independent invention of the mixed-flow counter-current heat exchanger. However, Rev. Robert Stirling had invented the same device, prior to Ericsson, so the invention is credited to Stirling. Stirling called it an "economiser" or "economizer", because it increased the fuel economy of various types of heat processes.
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The need to use two compressors when considering a booster set-up tends to increase the cost of a refrigeration system. Besides the gear's price, two staged systems need special attention over synchronization, pressure control and lubrication. To reduce these costs, special gear has been elaborated. subcooled economizer reduces the amount of gas compressors in the system.
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The control system can compare the temperature of the outside air vs. return air, or it can compare the enthalpy of the air, as is frequently done in climates where humidity is more of an issue. In both cases, the outside air must be less energetic than the return air for the system to enter the economizer mode.
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This phenomenon is notorious when taking in account that the evaporation temperature for a walk-in freezer at may be around . Systems with economizers aim to produce part of the refrigeration work on high pressures, condition in which gas compressors are normally more efficient. Depending of the application, this technology either allows smaller compression capacities to be able to supply enough pressure and flow for a system that normally would require bigger compressors; increases the capacity of a system that without economizer would produce less refrigeration, or allows the system to produce the same amount of refrigeration using less power. The economizer concept is linked to subcooling as the condensed liquid line temperature is usually higher than that on the evaporator, making it a good place to apply the notion of increasing efficiencies.
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A building's HVAC (heating, ventilating, and air conditioning) system can make use of an air- side economizer to save energy in buildings by using cool outside air as a means of cooling the indoor space. When the temperature of the outside air is less than the temperature of the recirculated air, conditioning with the outside air is more energy efficient than conditioning with recirculated air. When the outside air is both sufficiently cool and sufficiently dry (depending on the climate) the amount of enthalpy in the air is acceptable and no additional conditioning of it is needed; this portion of the air-side economizer control scheme is called free cooling. Air-side economizers can reduce HVAC energy costs in cold and temperate climates while also potentially improving indoor air quality, but are most often not appropriate in hot and humid climates.
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Geothermal plants do not need boilers because they use naturally occurring steam sources. Heat exchangers may be used where the geothermal steam is very corrosive or contains excessive suspended solids. A fossil fuel steam generator includes an economizer, a steam drum, and the furnace with its steam generating tubes and superheater coils. Necessary safety valves are located at suitable points to relieve excessive boiler pressure.
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Finally, there was a small Electric Runabout, the "Economizer," which was a personnel carrier only. The company manufactured four passenger vehicles for use at the 1964-65 New York World's Fair. This custom model was called an "Escorter" and a total of 150 were made. In 1966, the Hawk family of Kalamazoo, who had owned a controlling interest in the company since 1953, bought out the remaining shares.
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The heat recovery boiler is item 5 in the COGAS figure shown above. Hot gas turbine exhaust enters the super heater, then passes through the evaporator and finally through the economiser section as it flows out from the boiler. Feed water comes in through the economizer and then exits after having attained saturation temperature in the water or steam circuit. Finally it flows through the evaporator and super heater.
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Steam turbine plant lay out with dual pressure heat recovery boiler In order to remove the maximum amount of heat from the gasses exiting the high temperature cycle, a dual pressure boiler is often employed. It has two water/steam drums. The low- pressure drum is connected to the low-pressure economizer or evaporator. The low-pressure steam is generated in the low temperature zone of the turbine exhaust gasses.
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However, an economizer strategy is highly climate-dependent and necessitates careful control of humidity to avoid condensation. Critics, on the other hand, cite the shortage of rigorous research and testing to account for variations in climate, system design, thermal comfort and air quality to question whether UFAD is able to deliver improved energy efficiency in practice. Limited simulation tools, the shortage of design standards and relatively scarcity of exemplar projects compound these problems.
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Also, sample lines must be continuously sloping to avoid accumulation of samples in lines. (2) Line Material: Minimum Stainless steel SS316 Grade material must be used for sample Transport Lines. This is to avoid corrosion of lines which leads to wrong measurement and analysis. For High pressure and Temperature samples (Super heated steam, Reheated Steam, Saturated Steam, Separator drains, Feed water at Economizer inlets) SS316H must be used which withstand High Temperature of samples.
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In power stations, the same basic technology is employed for removal of from the flue gas of boilers used in power generation and industry. In general, the SCR unit is located between the furnace economizer and the air heater, and the ammonia is injected into the catalyst chamber through an ammonia injection grid. As in other SCR applications, the temperature of operation is critical. Ammonia slip is also an issue with SCR technology used in power plants.
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Modern-day boilers, such as those in coal-fired power stations, are still fitted with economizers which are descendants of Green's original design. In this context they are often referred to as feedwater heaters and heat the condensate from turbines before it is pumped to the boilers. Economizers are commonly used as part of a heat recovery steam generator (HRSG) in a combined cycle power plant. In an HRSG, water passes through an economizer, then a boiler and then a superheater.
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An economizer display takes advantage of the fact that refrigeration systems have increasing efficiencies at increasing pressures and temperatures. The power the gas compressor needs is strongly correlated to both the ratio and the difference, between the discharge and the suction pressures (as well as to other features like the refrigerant's heat capacity and the type of compressor). Low temperature systems such as freezers move less fluid in same volumes. That means the compressor's pumping is less efficient on low temperature systems.
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The in-plant ash-handling system conveys fly ash from hoppers under the baghouse, economizer, and air heater, as well as bottom ash from the combustor, to either of two silos located outside the powerhouse. Once in the silos, the ash is conditioned with water, loaded into trucks, and transported to a disposal site located next to the plant. Point Aconi uses a once-through circulating seawater system. Seawater is drawn from offshore at a depth of through a velocity cap intake structure.
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And between Limburg/Lahn and Wiesbaden and in the area of Darmstadt they also hauled goods trains. The firm of Krauss-Maffei initially delivered 13 engines in 1951 and a further 5 from 1955 to 1956. The first engine, with operating number 65 001, was retired as early as 1966. All the vehicles were given a welded, high-performance boiler. Operating numbers 65 001 - 65 013 were equipped with a surface economizer. Numbers 65 014 - 65 018 were given a mixer preheater.
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In its 2nd edition (July 1895) he gave the first description of the lightning detector invented earlier by Alexander Popov (the device was also a prototype of the first practical radio receiver). Lachinov's own inventions include a mercury pump, economizer for electricity consumption, electrical insulation tester (or defectoscope), optical dynamometer, a special types of photometer and electrolyser. One of his main achievements was a method of industrial synthesis of hydrogen and oxygen through electrolysis (1888). Dmitry Lachinov is great-grandfather of physical chemist Mikhail Schultz.
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The perfect efficiency would be a Power usage effectiveness (PUE) of 1.0. The POD 240a has a refrigerant-based air cooled HVAC system with air-side economization When the ambient air conditions are cool enough, the 240a uses economizer or free air mode—where outside air can be taken in and circulated inside the modular data center to cool the IT equipment.Clark, Jack, “HP to announce free-cooled datacentre Pod in June,” ZDNet, May 2011McNevin, Ambrose "An in-depth look at HP's EcoPOD," DacenterDynamics, June 15, 2011.
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Subcooling phenomena is intimately related to efficiency in refrigeration systems. This has led to a lot of research on the field. Most of the interest is placed in the fact that some systems work in better conditions than others due to better (higher) operating pressures, and the compressors that take part of a subcooling loop are usually more efficient than the compressors that are having their liquid subcooled. Economizer capable screw compressors are being built,Bitzer Kühlmaschinenbau GmbH, Bitzer Product Range A-201-2.
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Some systems include an "economizer mode", which is sometimes called a "free-cooling mode". When economizing, the control system will open (fully or partially) the outside air damper and close (fully or partially) the return air damper. This will cause fresh, outside air to be supplied to the system. When the outside air is cooler than the demanded cool air, this will allow the demand to be met without using the mechanical supply of cooling (typically chilled water or a direct expansion "DX" unit), thus saving energy.
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The energy assessment of UFAD systems is a not fully solved issue, which has led to numerous research projects within the building science and mechanical engineering community. Proponents of UFAD point to the lower fan pressures required to deliver air in a building via the plenum as compared to through ducts. Typical plenum pressures are (0.1 inch of water column) or less. The improvements in cooling-system efficiency inherent in operation at higher temperatures save energy, and relatively higher supply air temperatures allow longer periods of economizer operation.
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APS Bussinss Service, Refrigeration Efficiency Measures Recently, machines exclusively designated for this purpose have been developed. In Chile, the manufacturer EcoPac Systems developed a cycle optimizer able to stabilize the temperature of the liquid line and allowing either an increase in the refrigeration capacity of the system, or a reduction of the power consumption.Pesca y Medioambiente Nº45, New Challenges on Refrigeration, Cycle Optimizers. Such systems have the advantage of not interfering with the original design of the refrigeration system being an interesting alternative for expanding single staged systems that do not possess an economizer compressor.
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By late September, the Joint Committee on Reduction of Non-essential Federal Expenditures was in operation with Senator Byrd as Chairman; it built his national reputation as an economizer. By the 1950s Byrd was one of the most influential senators, serving on the Armed Services Committee, and later as chairman of the Finance Committee. He often broke with the Democratic Party line, going so far as to refuse to endorse the reelection of liberal President Harry S Truman in 1948. He also refused to endorse Adlai Stevenson in 1952.
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Photo by Charles O'Rear for Documerica (1972). At full capacity, the plant consumed of coal per day. Ash was collected from the bottom of the steam generating units (bottom and economizer ash) and captured via electrostatic precipitation from the plant's stack (fly ash); 70% of the plant's total ash was fly ash, and almost all of the fly ash was sold to be used as a concrete additive. Approximately of bottom ash and of sludge were placed in an onsite landfill each year; the disposal site, named Ash Canyon, was approximately in area.
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The ATMEA1 reactor is an about 1200 MWe generation III+ pressurized water reactor with three coolant loops and a thermal power level of 3,150 MWth. The design has high thermal efficiency (typically 10% higher than currently operating reactors), a 60-year service life and a load-following capability. The reactor can be set to a 12- to 24 month operational cycle. The ATMEA1 reactor's systems and components were previously developed by AREVA and MHI for the EPR and APWR, including steam generators with axial economizer and TT690 tubes, advanced accumulators and reactor internals with Heavy Neutron Reflector.
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The economizer also prevents flooding of the boiler with liquid water that is too cold to be boiled given the flow rates and design of the boiler. A common application of economizers in steam power plants is to capture the waste heat from boiler stack gases (flue gas) and transfer it to the boiler feedwater. This raises the temperature of the boiler feedwater, lowering the needed energy input, in turn reducing the firing rates needed for the rated boiler output. Economizers lower stack temperatures which may cause condensation of acidic combustion gases and serious equipment corrosion damage if care is not taken in their design and material selection.
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Condensing water is then reused for another cycle. In the process, water is preheated six times, raising its temperature from to , and goes through a deaerator and an economizer before entering the boiler at a temperature of , close to the boiling point under pressure. Each boiler is long and wide at its base and rises to , the equivalent of a 13-floor building. At the top, a long steam drum separates water and saturated steam. The boiler is heated by 16 burners, four in each corner, which can be retracted and tilted to control the steam temperature. The steam becomes an ideal gas at and a pressure of 12.75 MPa (1,850 PSI) after being forced into the superheater.
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The industrial application for the project was a knitwear factory operated by Bleyle of America Inc. STEP provided a large part of the electricity for the facility, displacing fossil fuels normally used to generate power to run the factory. STEP also provided process heat for absorption air conditioning within the building, as well as steam (downstream from the turbine) for pressing the knitwear products. The building was designed with a series of features for energy efficiency, including reduced height to minimize wall area and interior volume, a 4-ft insulating earthen berm around the building, north-south orientation, heavily insulated roof and walls, high-efficiency fluorescent lighting, energy-efficient production equipment, and an air conditioning system with an economizer cycle.
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Each steam generator has 13,102 Inconel 690 tubes; this material improves resistance to stress corrosion cracking compared to the Inconel 600 used in prior designs. Like the late-evolution System 80+ design, the steam generator design incorporates an integral feedwater economizer, which pre-heats feedwater before it is introduced into the SG. Compared with the OPR-1000 design, the steam generator features a larger secondary feedwater inventory, extending the dry-out time and affording more time for manual operator intervention, should it be needed. The design tube plugging margin is 10%, meaning the unit can operate at full power with up to 10% of the SG tubes plugged. Each of the two main steam lines from the steam generator contain five safety valves, a main steam relief valve and one isolation valve.
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However, it soon had to compete with newer and quicker performance versions of the Vauxhall Cavalier (Opel Ascona) and Ford Sierra. Model year 1982 saw the introduction of several changes to the entire lineup of 18 models, shown in late 1981: the negative offset front suspension, previously available only on the Turbo and Diesel models, was made standard. The front indicator lenses were changed from orange to clear, bumpers and door handles were switched from chrome to black polyester, and the seats were restyled to provide more space in the rear seats. Model-specific changes included the available option of a five-speed gearbox on the TL; the GTL received an "economy-tune" version of the engine, as well as a five-speed gearbox, higher final drive ratio, electronic ignition and an "economizer" gauge.
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Among other inventions are the gas economizer which became the most famous and productive of his patents, and the intake horn, which was soon copied by the majority of countries. He held a demonstration of this invention by attaching it to a car and touring Spain on a promotional tour, to the astonishment of the inhabitants of towns and cities on seeing a set of ten note loudspeakers playing regional music. That journey ended in the courtyard of the Palacio de Oriente, which he entered playing the Royal March, and shortly afterwards on the Champs Elysees in Paris at the Motor Show, playing the Marseillaise. Over the years, his business has occupied an important place in the world of ancillary automotive industries, being awarded the Silver Medal of Merit for his work in 1965.
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Another use of the term occurs in industrial refrigeration, specifically vapor-compression refrigeration. Normally, the economizer concept is applied when a particular design or feature on the refrigeration cycle, allows a reduction either in the amount of energy used from the power grid; in the size of the components (basically the gas compressor's nominal capacity) used to produce refrigeration, or both. For example, for a walk-in freezer that is kept at , the main refrigeration components would include: an evaporator coil (a dense arrangement of pipes containing refrigerant and thin metal fins used to remove heat from inside the freezer), fans to blow air over the coil and around the box, an air-cooled condensing unit sited outdoors, and valves and piping. The condensing unit would include a compressor and a coil and fans to exchange heat with the ambient air.
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When needed, the bay water is moved to a titanium heat exchanger, of which the building has two, where it is either used to heat or cool water that is cycled through a system of thermally activated radiant slabs. There are of plastic tubing in the radiant heating system in the floor, creating 82 different heating and cooling zones with distinct control systems. After the bay water passes through the heat exchangers, it is returned to the San Francisco Bay as allowed by a permit issued by the California Regional Water Quality Control Board. Most of the energy savings are expected to come from using the bay water as a heat sink for the building’s cooling needs. When the temperature of the bay water is below that of the chilled water return from the radiant pipes, which is the case for most of the year in the Bay Area’s temperate climate, the system works in waterside economizer mode. In this mode, the cooling loads are met either entirely or partially through passive heat exchange between the colder bay water and the warmer return water, greatly reducing the building’s energy needs.
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